It happened as the woman was driving eastbound on the Eisenhower under an overpass near Kostner just after 6:30 Wednesday night.
The driver says she never saw anyone suspicious on the overpass or along the side of the road, but she remains convinced her rear window was smashed by someone with ill intentions.
Holly Tlusty was still cleaning glass out her SUV Thursday as a result of a shattered backseat window.
"The sound was really loud. It was like taking a pane of glass and just dropping it 4 feet and hearing that crash," said Tlusty.
It happened as Tlusty was driving inbound on Interstate between Cicero and Kostner.
The Downers Grove wife and mother says she was driving 55 mph in one of the center lanes when the window shattered.
"I'm under attack? I mean, honestly, I didn't know what was going on," said Tlusty. "I didn't know if someone was shooting at me or somebody threw a brick through my window."
Tlusty looked to the right and says the driver next to her appeared as stunned as she was.
Tlusty called police after exiting the expressway and says, based on the extent and location of the damage, the responding officer told her it could have been caused by a pellet gun.
"He said well if it was a brick or a stone or rock, we would have found it inside the car," Tlusty said. "But there's nothing in the car...The officer told me that this is an area where there's punk kids that hang out and take shots at cars or throw rocks at cars."
Officially, a Chicago Police spokesperson Thursday said the cause of the damage, and whether it was the result of vandalism or simply an accident, could not be determined...
But the incident comes about a week after an alleged rock-throwing incident less than two miles away on the Ike.
Motorist Wilbert Crosby says, when his windshield was shattered by a 12-year-old boy on the Kedzie overpass, he confronted him and brought him to police.
"I took him in the station, and at the same time I was trying to explain to him that there's repercussions for everything that you do," said Crosby.
Tlusty says she is just glad she wasn't hurt and that none of her children were in the vehicle with her.
"I could have lost control of the car when it happened, freaked out, and ran into somebody else. Somebody else could have gotten hurt, too," Tlusty said.
Other than the incident involving Crosby, police say they have not received any other reports of rock throwing in the air.
Tlusty said she decided to speak to ABC7 Thursday so that other drivers could be warned.